This invention relates to an apparatus for coupling and aligning a record disk to the drive spindle in a disk drive.
The use of flexible magnetic disks or "floppy disks" to store and retrieve data has become very popular in the field of magnetic data processing. These disks are not typically part of the disk drive unit but are typically inserted and removed from the disk drive as needed. Typically the disk is enclosed in a flat rectangular cartridge having an opening which exposes the central portion of the disk to a drive means within the disk drive. Once the disk is inserted into the disk drive, it is necessary to engage the disk with the motor spindle so that the disk can be rotated.
Due to the portability of the floppy disks currently in use, the disk drive must contain an apparatus for aligning and rotating the disk once the cartridge is inserted into the drive. Such a disk centering and rotating apparatus should have the ability to positively and effectively center the disk with respect to the axis of rotation of the drive spindle and maintain that position during rotation of the disk. Other objectives of such a centering and aligning apparatus are simplicity, low cost and minimization of wear on the disk and the drive apparatus.
The prior art has been relatively unsuccessful in achieving these objectives. Apparatus disclosed by the prior art have been generally complex and have caused wear of the floppy disk. This wear of the disk frequently results in further difficulty in achieving the proper alignment between the disk and the drive spindle. One of the major draw backs of the prior art is the use of devices which transfer energy from the motor spindle to the disk by clamping the disk surface between two rotating members. The use of a clamping device such as this generally requires that the clamping surfaces be opened when the disk is inserted into the disk drive and closed when the disk is in its proper position. The prior art also required relatively elaborate means for positioning the disk relative to the clamping means prior to closing the clamping means on the disk. These features of the prior art resulted in bulkier and more expensive disk drives and increased wear and tear on the floppy disks. For example, several prior art apparatus use a magnetic means to center the disk hub on the motor spindle. See U.S. Pat. No. 3,975,768 - Jacques et al, U.S. Pat. No. 3,593,327 - Shill, U.S. Pat. No. 4,131,199 - Hatchet et al. Examples of prior art devices which use a clamping mechanism to rotate the disk are U.S. Pat. No. 3,940,793 - Bleiman, U.S. Pat. No. 4,125,883 - Rolf, U.S. Pat. No. 3,815,150 - Stoddard et al, U.S. Pat. No. 3,678,481 - Warren et al.